The movie that makes feel all summery is Picnic (1955) starring Kim Novak and William Holden. I love her pink poofy dress and how she would lounge in the summer heat on this wooden swing.
I found these Anthropologie dresses which are perfect for modern day Kim Novaks.
Marmalade Dress ($158)
Swimfins Dress ($118)
Nectar Halter Dress ($218)
Tropical Spray Dress ($248)
Jacana Silk Dress ($250)
Groves of Palm Dress ($158)
By the way, if you don't have time to rent the movie, watch the dance scene here set to "Moonglow". Just sublime!